We have investigated possible interactions between ACP1 and Hp concerning their effects on the susceptibility to convulsive disorders. 129 children with idiopathic generalized epilepsy with tonic clonic seizures (IGE) and 127 controls were studied in the population of Rome. There is a significant interaction between Hp and ACP1 concerning their effects on epilepsy. The association of Hp with epilepsy depends on the ACP1 genotypes. In carriers of the *B/*B genotype of ACP1 the risk of epilepsy is much lower in Hp *1/*1 children than in other Hp types. This is not observed in carriers of other ACP1 types.The present data suggest an epistatic action of ACP1 concerning the effect of Hp on the susceptibility to convulsive disorders.